JPS6116857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dual-tube shock absorber that separates oil and gas.

In general, in dual-tube gas-filled shock absorbers that have an outer tube forming the gas chamber and an inner cylinder forming the oil chamber, the oil chamber and gas chamber must be separated or sealed. Since this is a gas shaft seal instead of an oil shaft seal, gas tends to escape to the outside, and as a result, the damping force waveform is likely to be disturbed. Also, as the piston rod moves up and down, gas enters the cylinder from the bearing guide.
Oil and gas mix in the cylinder, creating air rays, which disrupts the damping force waveform and causes play in operation, causing abnormal noise. For this reason, as a way to solve this problem, for example,
A hydraulic shock absorber as seen in Japanese Patent No. 25495 is known. In this type, a lip serving as a check valve is integrally formed in the seal portion to allow the flow of oil from the cylinder to the gas chamber, while blocking the flow of gas from the gas chamber to the cylinder. However, in such a hydraulic shock absorber, the piston rod, which is slidably installed inside the shock absorber, is constantly bent during operation, generating a twisting moment, and the lip provided integrally with the sealing member must make a corresponding movement. However, since the lip is provided integrally with the sealing member, the above movement is restricted by the lip, resulting in twisting, etc., which not only deteriorates followability but also reduces durability and sealing performance. is also having a negative impact. Furthermore, since the sealing member and the lip are integrated, the lip and the sealing member must be made of the same material, which causes various problems in that the check mechanism cannot be used satisfactorily.

Therefore, the purpose of the present invention is to solve these conventional drawbacks by providing a double-tube shock absorber that separates oil and gas, which has significantly improved durability and followability of the check valve lip, and has improved check function. The goal is to provide the following. To achieve this purpose,
The structure of the present invention includes a cylinder forming an oil chamber, an outer tube provided on the outer periphery of the cylinder, a gas chamber formed above between these cylinders and the outer tube, and a gas chamber provided movably within the cylinder. A piston rod having one end protruding from the cylinder to the outside via a bearing and a seal member that seals the inside and outside of the cylinder, and a piston rod that is connected between the gas chamber and the oil chamber in the cylinder from the oil chamber in the cylinder to the gas chamber side. In a shock absorber equipped with a check valve mechanism that allows oil to flow only to the piston rod, the check valve mechanism is constituted by a member separate from the seal member, and the check valve mechanism is configured to be a member separate from the seal member, and there is a gap between the bearing and the seal member without contacting the piston rod. At the same time, the proximal end side of the check valve mechanism is pressed against the lower part of the sealing member via a spring supported on the upper surface of the bearing, and the distal end thereof is seated in and out of the valve seat formed in the bearing. It is characterized in that it is brought into contact so as to be able to do so.

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, in the shock absorber, a bearing 25 is fixed to the upper end of a cylinder 1, a piston rod 3 is movably inserted into the center of the bearing 25, and an oil chamber 4 is defined within the cylinder 1.

Above the bearing 25 is a packing cover 26.
An outer tube 10 concentric with the cylinder 1 is fixed to this cover 26. A gas chamber 11 is defined above between the outer tube 10 and the cylinder 1, and the gas chamber 11 and the oil chamber 4 are separated from each other. This allows gas and oil to be separated. However, the lower part of the gas chamber 11 is filled with oil.

A gasket 27 as a sealing member is disposed inside the cover 26, and the piston rod 3 slidably passes through the bearing 25 and the center of the gasket 27, and a plurality of lips 2 provided on the inner periphery of the gasket 27.
8 is in sliding contact with the piston rod 3 to prevent oil leakage and dust infiltration. An oil chamber 37 of an arbitrary size is formed between the packing 27 and the bearing 25 to temporarily store oil flowing out from the gap 13 between the bearing 25 and the piston rod 3. A through hole 33 is bored in the bearing 25, and this hole 33 allows a chamber 34 in the cover 26 to communicate with the gas chamber 11.

A check valve mechanism V which is in a non-contact state with the piston rod 3 is disposed below the gasket 27, and a plate 35 that holds the gasket and constitutes the base end of the check valve mechanism V presses against the gasket via a spring 32. One end of the spring is supported on the upper surface of the upper annular recess of the bearing 25.

A lip-shaped check valve 36 constituting the front end of the check valve mechanism is provided on the tip side of the plate 35, and this check valve 36 contacts the upper annular valve seat 38 of the bearing 25 so that it can be seated on and taken off from it, that is, it can be opened and closed. ing.

The check valve 36 is constituted by a separate member cm ² from the seal member, and the check valve 36 is disposed between the bearing 25 and the packing 27 which is the seal member.
It extends in the axial direction and is movable in the radial direction.

The valve seat 38 is formed by the outer annular tapered surface of a truncated conical projection 39 projecting from the upper center of the bearing 25, but the shape of the valve seat 38 is not limited to that shown in the drawings. Also plate 35
The connection between the check valve 36 and the check valve 36 is not necessarily limited to the shape and fixing method shown in the drawings. The check valve mechanism V is openable and closable in the middle of the gap 13 - oil chamber 37 - chamber 34 - hole 33, which is a passage that communicates the oil chamber 4 and the gas chamber 11.
It allows oil to flow to the side, but acts as a one-way valve to prevent gas from flowing out from the gas chamber 11 to the oil chamber 4 side.

In the illustrated embodiment, a check valve 36 is disposed at the gas chamber side mouth end of the oil chamber 37 so as to be openable and closable.

The gas pressure in the gas chamber 11 acts on the back side of the check valve 36 from the hole 33-chamber 34, and in order to press it against the valve seat 38, the gas in the gas chamber 11 flows through the oil chamber 37 and the chamber 4.
Does not leak to the sides.

As the piston rod 3 slides, oil in the oil chamber 4 leaks from the gap 13 between the bearing 25 and the piston rod 3 into the oil gap 37, and this leaked oil is temporarily stored in the oil chamber 37. The check valve 36 is flexible and contacts the valve seat 38 with a slight set load due to the elasticity of the check valve 36. On the other hand, when the oil chamber 37 is filled with oil and the internal pressure rises, the check valve 36 bends outward and opens, allowing the oil in the oil chamber 37 to flow from the chamber 34 to the hole 33 into the gas chamber 11. It is something.

According to the present invention, the following effects are achieved. In other words, since the seal member and the check valve mechanism are separate and independent members, even if a bending or twisting moment occurs in the seal member, the check valve mechanism will not follow the movement of the seal member. The check valve at the tip does not need to be twisted. You can select the material that is most suitable for the check valve mechanism regardless of the sealing material, and the opening pressure can be freely controlled accordingly. The pressure applied to the seal can be optimally controlled by synchronizing the increase in the amount of ejection from the gap and the decrease in rubber hardness due to high temperatures. Furthermore, by removing the check valve mechanism, it can be easily constructed as a standard non-gas-filled shock absorber. Since the check valve mechanism is in a non-contact state with the piston rod, it is not affected by the vibrations of the piston rod and can improve durability. The check valve mechanism can be assembled independently of the piston rod, making assembly easy. Since there is nothing to prevent the check valve from deflecting outward, the response when opening is good.

[Brief explanation of the drawing]

The accompanying drawing is a partially cutaway vertical side view of a shock absorber according to an embodiment of the present invention. 1...Cylinder, 3...Piston rod, 4...
... Oil chamber, 10 ... Outer tube, 11 ... Gas chamber, 25 ... Bearing, 27 ... Seal member, 36 ... Check valve, 37 ... Oil chamber, 38 ...
...Valve seat, V...Check valve mechanism.

Claims (1)

[Claims] 1. A cylinder forming an oil chamber, an outer tube provided on the outer periphery of the cylinder, a gas chamber formed above between these cylinders and the outer tube, and a cylinder provided movably within the cylinder and having one end. between the piston rod that protrudes from the cylinder to the outside through a bearing and a seal member that seals the inside and outside of the cylinder, and the gas chamber and the oil chamber in the cylinder. In a shock absorber equipped with a check valve mechanism that allows flow, the check valve mechanism is constructed of a member separate from the seal member and is disposed between the bearing and the seal member without contacting the piston rod. The proximal end of the check valve mechanism is pressed against the lower part of the sealing member via a spring supported on the upper surface of the bearing, and the distal end of the check valve mechanism is designed so that it can be moved into and out of the valve seat formed on the bearing. A dual-tube shock absorber that separates oil and gas by making them contact each other.